Communications system



Feb. 8, 1949. R. ADLER COMMUNICATION SYSTEM 3 Sheets-Sheet 1 Filed March 15, 1946 Fig. 7

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His ATTORNEYS Patented Feb. 8, 1949 COMMUNICATIONS SYSTEM Robert Adler, Chicago, Ill., assignor to Zenith Radio Corporation, a corporation of Illinois Original application February 5, 1945, Serial No.

Divided and this application March 13, 1946, Serial No. 654,049

19 Claims.

This invention relates to communication systems, and more particularly to such systems in which the phase or frequency of a carrier Wave is modulated in accordance with intelligence to be transmitted.

This application is a division of my copending application, Serial Number 576,227 filed February-5, 1945, for Communications System.

It is usual to modulate the frequency of the carrier wave by causing the oscillation generator which generates the carrier wave to change its operative frequency in accordance with the signal or intelligence to be transmitted. Such a system is inherently liable to allow the average or center frequency of the modulated carrier wave to drlft, since the oscillator cannot be crystal controlled but must be sensitive to influences which cause its frequency to change. For communication work, and particularly for broadcast work, it is highly desirable to have the oscillation generator of a transmitter crystal controlled so that its average or mean frequency is maintamed-constant with a high degree of accuracy.

It is usual in phase modulation systems toprovide a crystal controlled oscillation generator which maintains a mean or average frequency of the transmitter constant with a high degree of accuracy, but there are other undesirable complications. Phase modulation, if used without modification, requires enormously wide frequency bands for its operation if any but relatively low signal frequencies are transmitted. That is, it is a characteristic of a phase modulation system that carrier wave frequency is shifted in an amount proportional not only to instantaneous signal intensity but also to instantaneous signal frequency. of more practical importance is the fact that arrangements so far known for producing phase shift of the carrier wave in response to the instantaneous intensity of a signal have been capable of shifting the phase of the carrier wave only a fraction of one-half cycle at the most, and to obtain substantial frequency modulation it has been necessary to multiply the carrier wave frequency many times, making it necessary to use large numbers of multiplier tubes in any system in which it was desired to provide a substantial amount of frequency modulation in comparison with the highest signal frequency to be transmitted. Furthermore, it hasv been necessary to' provide special circuit arrangements for modifying the modulating signal voltage in such phase modulation systems if it were desired to make them operate in such a way as to produce frequency modula- It is an object of my invention to provide a new and improved system for producing such types of modulation in which fewer parts are required and over-all simplicity and cheapness is obtained.

It is also an object of my invention to provide an arrangement which is capable of producing timing modulation (such as phase or frequency modulation) with a minimum number of vacuum tubes and with sufiicient simplicity that a transmitter incorporating my invention may be readily utilized invehi'cles and will require minimum power supplied by such vehicles.

It is a more specific object of my invention to provide a phase modulation system in which the need for large amounts of signal frequency modification is' obviated.

Another object of my invention is to provide a frequency modulation system in which crystal control of the oscillation generator, equivalent to that heretofore obtained in phase modulation systems, is provided with a maximum of simplicity and a minimum number of discharge devices.

A still more specific object of my invention is to provide a special electron discharge device especially useful in such systems and which is capable of producing a phase shift in a carrier wave of much more than one-half cycle in response to a modulated signal.

In general, it is also an object of my invention to provide such a system and its various component parts, in which the parts are especially designed to cooperate with each other in the system to carry out a maximum number of functions necessary and desirable in such systems with a minimum number of such parts.

The features of the present invention which are believed to be novel are set forth with particularity in the appended claims. The present invention itself, both as to its organization and manner of operation, together with further objects and advantages thereof may best be understood by reference to the following description taken in connection with accompanying drawings in which:

Figure 1 illustrates a section, partly broken away, of a special electron discharge device useful in carrying out the invention;

Figure 2 is a perspective view of a detail of Figure 1;

Figure 3 is a developed view of a portion of the device of Figure 1;

Figure 4 is a developed view of another portion of the device of Figure 1;

Figure 5 is a perspective view which is helpful in certain operating characteristics of the device of Figure 1;

Figure 6 is a view similar to Figure under certain different operating conditions;

Figure 7 is an elevational view of a detail of Figure 1.

Figure 8 illustrates an alternative form of a special electron discharge device useful in the invention, and shows sections of the device taken at right angles to each other;

Figure 9 shows a modified form of the device somewhat similar to that illustrated in Figure 8;

Figures 10 and 11 illustrate a simple form of the special discharge device useful in the invention and shows certain operating characteristics thereof;

Figures 12 through 15 illustrate still other modified forms of the special electron discharge device useful in the invention;

Figure 16 shows schematically a circuit arrangement including a special discharge device and arranged together therewith to carry out .certain of the aspects of the invention; and

Figure 17 illustrates still another circuit arrangement including a similar special electron discharge device and arranged together therewith to carry out certain other aspects of the invention.

In a phase modulation system arranged according to this invention a special electron discharge device is utilized in which a beam of electrons is generated, the electron distribution of such beam being periodically altered thereby to cause an electron density wave, which may be either transverse or longitudinal, to move past or across an output electrode recurrently at a speed controlled in accordance with the frequency of a carrier wave whose phase or frequency is to be modulated. This wave is advanced or retarded in its passage recurrently past or across the output electrode by a magnetic field produced in response to modulating signals. When the magnetic field is of one polarity the electron density wave is advanced ahead of the position it would assume in the absence of the magnetic field, such position being recurrently moved past the output electrode, and current generated from the output electrode by the passage of the wave past it is correspondingly advanced in phase. Similarly, when the magnetic field is of the opposite polarity, the wave is retarded during its passage across the electrode and the phase of the current generated in the electrode is correspondingly retarded.

In Figure 1 a preferred form of this special electron discharge device is illustrated in which within an evacuated envelope I, acathode2,focusing anodes 3 and 4, electron beam generating and altering control electrodes 5 and 6, focusing anodes I and 8, a first anode electrode 9, a suppressor electrode l0, and a second anode electrode l l, are supported. Cathode 2, as illustrated, is of the indirectly heated type and includes a metal cylinder around the central portion of which an electron emissive layer I 2 is coated, and inside of which a filamentary heating element I 3 is placed. The filamentary heating element [3 is supplied with suitable heating current through a twisted pair of conductors l4, so that the tubular cathode 2 is heated sufficiently to cause the electron emissive coating l2 to emit electrons.

The two focusing anodes 3 and 4 surround the tubular cathode 2 and are coaxial therewith, and they present adjacent edges toward one another between which there is a gap through which electrons from the emissive surface 12 may be projected radially from the tubular cathode 2. The focusing anode 3 is connected through a suitable conductor IE to a conductor l6 which is connected between the focusing anode 4 and a suitable source of potential which is positive with respect to the cathode 2, so that electrons which are attracted by the focusing anodes 3 and 4 from the surface l2 to a large extent pass through the gap between the anodes 3 and 4 and are thus projected radially from the layer l2.

The control electrodes 5 and 6, to be described more fully hereinafter, lie on opposite sides of the circular disc of electrons emitted radially from the surface l2. These control electrodes 5 and 6 are suitably sub-divided into small control elements or surfaces to which suitable multiphase high frequency potentials are applied to cause the formation of an electron beam and to alter the electron distribution of the electron beam so formed thereby to cause an electron density wave, which is of a transverse nature in this preferred embodiment, to move circumferentially around the emissive layer l2.

The potentials of the focusing anodes 3, 4 and 1, 8 are adjusted so that this radial disc of electrons is focused so that the disc has a sharp edge like that of a discus at a certain radius from the cathode 2. The anode 9 surrounds the cathode 2 concentrically therewith and its radius is such that it intercepts the disc of electrons in a sharply defined line except where there are cut-out portions between the elemental areas l1, I8, l9, and 20, etc. These elemental areas of the anode 9 are alternately disposed along opposite sides of a line which would be defined by the sharply focused edge of the disc of electrons which would be formed without any potential applied to the control electrodes 5 and 6.

Electrons pass through the apertures in the first anode 9 and then through the suppressor electrode l0 and are finally collected upon the second anode electrode II which is connected through a suitable conductor 2| with a source of potential which is positive with respect to the cathode 2.

The entire assembly of elements is maintained in proper spaced relation for the described operation by a pair of mica discs 22 and 23 which are centrally apertured to maintain the cathode 2 in coaxial relation with the envelope I. The focusing anodes 1 and 8 are respectively fastened to these mica sheets 22 and 23 by suitable fastenin means such as the illustrated rivets 24 and 25. Two spacing rings 26 and 21, of suitable material, lie concentrically within the focusing anodes I and 8 against the mica sheets 22 and 23 and maintain a pair of insulating rings 28 and 29 within suitable folds of the focusing anodes I and 8. Rings 28 and 29 in turn support the focusing anodes 3 and 4. The control electrodes 5 and 6 are respectively supported on conducting and supporting rings 30, 3|, 32, 33, 34 and 35, which are in turn supported respectively on the insulating rings 28 and 29. The conducting and supporting rings 33, 34 and 35 are connected through suitable conductors 36, which extend through the insulating ring 29 and through the mica disc 23 to three corresponding conductors 31, which extend through the mica disc 22 and through the insulating ring 28 to respective connections with the conducting and supporting rings 30, 3| and 32. Multiphase voltages impressed on the three conductors 31 form an electrostatic field between the control electrodes and 8 in such a manner as to modify the shape of the electron disc passing between them as described more fully hereinafter.

The focusing electrodes 1 and 8 not only act in focusing the disc of electrons projected radially from the surface I2 but also act to concentrate magnetic flux produced by means described later between their adjacent edges through the electron disc. To this end the anodes I and 8 are made of ferromagnetic material. The rivets 24 and 25 respectively hold magnetic flux directing members 38 and 39 against the mica pieces 22 and 23 in such a position that magnetic flux developed by current flowing through a coil 40 wound around the envelope l concentrically with the cathode 2 passes inwardly through the flux directing member 38 and anode I, and then across the gap between the anodes 1 and 8 and onward through the anode 8 and flux directing members 39, and thus back around the coil 48. The action of this flux across the gap between anodes I and 8, upon the electron disc is to impart to individual electrons within the disc velocity components which are tangential to and perpendicular to the planes of circles centered around the cathode 2.

The anode 9 is formed with inwardly turned flanges 4| and 42, which are respectively fastened to the mica discs 22 and 23 by fastening means such as rivets 43 and 44.

The anodes 1 and 8 are maintained at a potential positive with respect to cathode 2 by connection through the rivets 24 and 25 and the flux directing members 38 and 39 and conductors 45 and 48 to a suitable source of such positive potential. The anode 9 is connected through suitable conductors 41 and 48, connected with rivets 43 and 44, to a suitable source of potential positive with respect to cathode 2.

The suppressor electrode I8 is wound on suitable supporting posts, such as the post 49, which have ends projecting respectively through the mica disc 22 and 23, and the suppressor electrode is connected through those posts and through a conductor 58 to the cathode 2.

The second anode electrode H is supported on similar supporting posts such as the post 5| whose opposite ends project through the mica discs 22 and 23 and this electrode l l is connected through the post 5| and conductor 2| and through a load to a suitable source of potential suificiency positive with respect to the cathode 2 to assure that no electrons passing through the suppressor electrode II! can return to the electrode 9.

A cylindrical shielding element 52 is fastened around the edges of the mica discs 22 and 23 and is connected through a conductor 53 and through conductor 50 to the cathode 2.

The entire assembly is supported by conventional means, not illustrated, concentrically within the envelope I, and such conventional means may, for example, be spring strips punched out of the shield 52 and bent outwardly to press against the envelope I and maintain the whole assembly substantially concentric within the envelope.

The sectional view shown in Figure 1 shows the Two others 54 the mica discs 22 and 23 in a direction at right angles to that in which the members 38 and 39 extend. It is to be understood that the entire arrangement is symmetrical about the cathode 2.

By way of example, with the particular construction shown, which is one of the preferred forms of the special electron discharge device required for the use of this invention, the following electrode potentials are approximately those necessary to form the described electron disc. The anodes 3 and 4 are maintained about 12 volts positive with respect to cathode 2. The control electrodes 5 and 6 are maintained about 35 volts positive with respect to cathode 2, and the anodes I and 8 are maintained about 55 volts positive with respect to cathode 2. The second anode electrode II is preferably maintained at a higher positive potential with respect to the cathode 2 than any other electrode in the device in order to maintain a uniform electrostatic field inside the anode electrode 9, and a voltage of about 250 volts positive with respect to cathode 2 is suitable where the anode electrode 9 is maintained at about volts positive wtih respect to cathode 2. The voltage of the anode 9 should be adjusted along with the voltages of the focusing anodes 3, 4, and 8 to cause the formation of the electron disc described so that the electrons in the disc focus in a sharp line at the surface of the anode 9. With such electrode potentials polyphase alternating voltages of the order of 10 volts may be impressed on control electrodes 5 and 6. In Figure 2 a detail of one portion of the control electrode 6 is illustrated in which the conducting and supporting rings 33, 34 and 35 appear in large scale to show the manner of their connection with the individual elements of the control electrode 6. These individual elements are numbered a, b and 0, consecutively and recurrently, and all elements numbered a are connected with the conducting and supporting ring 35. Similarly, all elements numbered b are connected with ring 34 and all elements numbered 0 with ring 33. Upon the application of a three phase voltage to the conductors 31 and thereby to the rings 33, 34 and 35, the control electrode elements which are numbered in groups a, b and c are excited in groups with the respective individual phase voltages of that three phase voltage. The entire control electrode 6, and similarly the control electrode 5, where it is to be excited with a three-phase voltage is formed of a number of the elements a, b, and c which is a multiple of 3, so that the numbers of elements in the three groups a, b and c are equal.

In Figure 3, there is shown a developed view around the circumference of control electrode 5 and 8 showing the individual elements of the control electrodes 5 and 6. The elements a, b and c of control electrode 5 are arranged in staggered relation with respect to the elements a, b and c of the control electrode 6 so that a three phase voltage applied to these two control electrodes creates an electrostatic field between them which at one point bends the electron disc toward electrode 5 and at another point cireumferentially around cathode 2 from that first point bends the electron disc in the opposite direction toward electrode 6. That is, an element 0 of electrode 8 is opposite a point midway between elements a and b of electrode 5. and an element a of electrode 8 is opposite a po nt midway "between elements b and c of electrode 5. Similarly, an element b of electrode 8 is opposite a point midway between elements 0 and a of electrode 5.

Consequently when voltages of three equally displaced phases are applied to the elements a, b and c, at a particular instant when the elements are most negative, the elements a and b are approximately at a potential which is half of their maximum positive value, and electrons passing between one element 0 and the opposite elements a and b are deflected sideways toward the elements a and b. Since in all cases electrons are therefore deflected in a direction parallel to the cathode 2 away from every element c in either of the control electrodes and 6, the electron disc is warped so that its edge, when it is viewed edgewise, appears scalloped.

If three phase voltages are applied to the element groups a, b and c of the electrodes 5 and 6, the potentials of the three groups constantly change so that the electrons of the disc are deflected in a direction parallel to the cathod 2 alternately in succession from each of the three element groups (1.,b and c of the control electrodes 5 and 6. In consequence, the convolutions or scallops on the edge of the electron disc appear to rotate around the cathode 2 as an axis in a manner analogous to the rotation of the magnetic field developed in a multiphase electric motor armature. In other words, periodic axial electron displacement in response to application of multiphase potentials to the control electrodes 5 and 6 causes a uniform velocity electron density Wave to progress continuously and recurrently along the path of the anode segments I1, l8, I9, 29, etc.

Usually the three phase voltage applied to the conductors 3'! will be of high frequency, such as is commonly used for carrier wave purposes, and the apparent revolution of the convolutions or scallops of the outer edge of the electron disc will be extremely rapid.

The apertures between the alternating opposite areas I1, l8, I9, 29, etc. of the anode 9 correspond exactly to the convolutions or scallops in the edge of the electron disc as described. That is, there are as many of the areas I1, I8, I9, 29, etc. in the anode 9 as there are elements in any one of the groups a, b or c of both of the electrodes 5 and 6 taken together. For example, as illustrated, there are twenty-four of the areas l1, l8, l9 and 29 of the anode 9, and there are twelve elements in each of the groups a, b and c in each of the control electrodes '5 and 6.

In Figure 4 the anode 9 is shown in developed form and a sinusodial line 56 is drawn about the line dividing the areas l1, l9, etc. on one side of the anode 9 from the areas I8, 29, etc. on the other side of the anode 9. The line 56 represents the thin convoluted edge of the electron disc where it is focused sharply on the anode 9. Of course, the line 56 represents the edge of the electron disc only at one particular instant. At such an instant inspection of the line indicates that some electrons from the disc impinge upon the segmental areas l1, I8, l9 and 29 of the anode 9 and other electrons of the disc pass through the apertures between those areas. At the instant represented by the line 56 more electrons pass through the apertures than those which impinge on the segmental areas and if the polarity and phase of the three phase voltage applied to conductors 31 .is such that the line 56 advances upwardly as shown on the anode 9, after a small fraction of a cycle the number of electrons impinging on the anode 9 increases and the number of electrons which pass through the apertures in the anode correspondingly decreases until such numbers are equal. At succeeding instants of time the number of electrons impinging on the anode 9 continues to increase until the line 56 intersects the contiguous corners of the areas l1, 19, etc., at which time all of the electrons in the electron disc impinge upon anode 9.

Thereafter, as the line 56 advances further electrons in increasing numbers again pass through the apertures in anode 9 and the number of electrons impinging upon anode 9 decreases with respect to time until the line 56 again intersects contiguous corners of the areas l1, l9. etc., at which time substantially all electrons pass through the apertures in anode 9 and a minimum number impinge upon it.

This action continues recurrently so that an alternating electron current is produced in the anode 9 of a frequency equal to the frequency of the three-phase voltage impressed on conductors 31.

As explained briefly in connection with a description of the coil 49 and the ferromagnetic focusing anodes l and 8, whenever current traverses the coil 49, flux passes between the edges of anodes 1 and 8 and thus through the electron disc. Since electrons in this disc are moving radially outward from the cathode 2, magnetic flux perpendicular to their path of travel induces additional electron motion in a direction mutually perpendicular to the magnetic flux and to the initial direction of electron travel, with the result that the convolutions of the edge of the electron disc at the anode 9 are advanced or retarded with respect to the positions they would have occupied in the absence of such a magnetic field. In consequence, current flowing through the "coil 49 in one direction or the other produces a corresponding advance or retardation in the phase of the current in the anode 9. Viewed in another way, the electron density wave progressing along 40 the path of the anode segments l1, l8, 19, 29,

etc, is accelerated or decelerated in accordance with amplitude variations of the modulating signal impressed on coil 49.

In Figure 5 there is a perspective View of a portion of the described electron disc as it would appear if it could be seen, at a time when no current is going through the coil 49. The line 56 forms the outer edge of the convoluted disc and the central portion of the disc is illustrated as having substantially a thickness equal to the length of the emissive cathode surface l2.

In Figure 6 the electron disc illustrated in Figure 5 is shown in the manner in which it would be modified in the presence of current flowing through the coil 49. As illustrated, individual electrons take paths to the line 56 which depart from the radii of the disc, that is electrons emitted from the emissive cathode surface l2 and thereafter deflected to one side or the other by the respective elements of the control electrodes 5 and 6 are further deflected circumferentially around the disc so that its edge convolutions are displaced circumferentially from the positions they would have occupied in the absence of current in the coil 49. Comparison of the shapes of the discs in Figures 5 and 6 makes immediately evident this deformation in the electron disc due to the flow of current in coil 49.

In Figure 7 a View in elevation of the control electrode 9, together with surrounding electrodes, taken from a plane perpendicular to the axis of cathode 2 illustrates more clearly the action of the second focusing anodes 1 and 8 in concentrating magnetic flux from coil 49 to cause displacement of the point of impingement of an electron substantially in proportion to the increase of magnetic flux intensity. In this figure elements corresponding with those in Figure 1 are given like reference numerals. The straight dotted line extending between cathode 2 and anode element l9 indicates the path of travel of an electron in the absence of a magnetic field, and the dotted line extending from the interception of the first line with the ferro-magnetic focusing anode 8 to the anode element l1 indicates how the path of electron travel is changed in the presence of a concentrated magnetic field between the ferro-magnetic focusing anodes I and 8. It is evident from the geometry of this figure that if the path of every electron were to extend radially from cathode 2 in the presence or absence of a magnetic field the displacement of the point of impingement of such path on one of the anodes would be proportional to the intensity of the magnetic flux inducing such displacement. To produce such displacement and maintain electron travel radial, magnetic flux would have to be concentrated at cathode 2. It is also evident that if the path of an electron is caused to deviate gradually from the straight dotted line extending to anode element l9 as by flux throughout the electron path, that path where it intercepts one of the anodes would be curved and it would intercept the anode at a point farther removed, from the point where the dotted line intercepts anode element l9 by reason of its gradual curvature. This can be seen more readily if it be first considered how this displacement would be affected if the two anodes lay in plane surfaces rather than in cylinders. Obviously, if the anode elements lay in plane surfaces there would be a critical amount of magnetic flux which would cause the electron path to curve sufficiently that it would never reach either anode and slightly less flux would cause the electron to reach one of the anodes at a point far removed from the point at which it would have impinged in the absence of magnetic flux. The same is true of cylindrical anodes.

By concentrating the curved portion of the path of electron travel in as short a distance as possible as near as possible to the center of the cathode 2 by means of concentrating the magnetic flux at such position, as for example by members 38 and 39 or by other suitable means, non-linearity caused by the disproportionality between magnetic flux intensity and resultant displacement of the point of impingement of an electron on one of the anodes is reduced substantially, with the result that in a practical discharge device of this type a sufficient amount of magnetic flux may be utilized with reasonably good proportionality between the total amount of that flux and resulting electron displacement to cause that displacement to be as much as the circumferential distance around three adjacent anode elements which correspond to two complete cycles of the alternating anode current which is generated in the anode elements by the passage of the electron density wave thereacross. That is, this discharge device is capable of producing a phase shift in a carrier wave transferred through it at least two full cycles (720) in either direction in response to modulating signal currents flowing through coil 48.

There is one important characteristic of a system which utilizes any of the special forms of electron discharge device in this invention in order to minimize distortion. In any form of such discharge device the electrostatic field pattern created by the control electrode structure must rotate at all points within itself at substantially uniform velocity. This can be achieved most easily by making the control electrode structure symmetrical with respect to the cathode and by placing the control electrode elements out of the path of the electron beam, as is done in the form of discharge device illustrated in Figure l, or by skewing the control electrode elements to make them appear substantially continuous with respect to the electron emission, or preferably by utilizing both of those two measures.

That is, in the form of electrode structure shown in Figure 2 the individual control elements a, b and 0 should be positioned, not radially, as shown but each-at some substantial angle to a line through the center of the cathode 2, the

angle being just enough so that each element a,

for example, subtends an angle whose apex is at the center of the cathode 2 approximately equal to 360 divided by the total number of the control elements a, b and c. It is preferred to arrange the control elements a, b and c in Figure 2 in this fashion when they are used in the device illustrated in Figure 1.

In Figure 8 there is illustrated an alternative form shown schematically, of a discharge device similar to that shown in Figure 1 but having the control electrode structure formed of wires lying within the electron stream coming from the cathode. In the schematic view a cathode 5! acts as a source of electrons and is surrounded by a control electrode structure 58 in the form of a squirrel cage. In the electrode structure 58 every 3.3 third conductor or control element is connected together and to one phase conductor of a three phase voltage supply in a manner similar to the connections of the elements a, b and c of Figures 1 and 2. It is to be understood that any multiphase source of voltage may be utilized to energize any of the control electrode structures illustrated, provided those structures are connected in a suitable manner to create a smoothly rotating electrostatic field.

Surrounding the control electrode structure 58 there is a first anode which includes anode elements 59, 68, 8|, etc. corresponding in number to the number of groups of three of the control electrode structure 58. These anode elements are spaced apart by distances substantially equal to their circumferential widths. A second anode 62 surrounds the anode formed of elements 59, 68, 5|, etc., and both of the anodes 59, 68, BI and 62 are maintained at positive potentials with respect to cathode 51 so that electrons projected from cathode 51 and formed into a beam by the control electrode structure 58, as the electron density wave progresses around the cathode 51, all impinge simultaneously either on the anode elements 59, 68 and (H or on the second anode 52. The action of the electrode structure 58 in setting up the electron density wave is substantially identical with the action of the electrode structure 5 and 6 of Figure 1 and does not here require explanation in detail. It is to be noted that the electron density wave set up by the structure of Figure 8 is longitudinal in nature, as contrasted with the transverse electron density wave induced by the structure of Figure 1.

Suitable provision, not illustrated in Figure 8, is made for the production of alternating magnetic flux extending parallel to the long axis of cathode 51 in the space between cathode 5'! and the first anode so that the electron paths, of which one is diagrammatically illustrated, are

ll bent in one direction or the other as illustrated by line 63.

In the right hand portion of Figure 8, like numbers being given to the elements illustrated in the two portions of that figure, cathode 51, control electrode structure 58, first anode 59, and second anode 62 are illustrated as having substantial length in the direction of the axis of cathode 51. While it is possible to induce a magnetic field in the space between cathode 51 and the first anode 59 by means of a simple coil placed coaxially with cathode 51 at one end of the device, such a coil has a disadvantage generally that the magnetic flux is distributed more or less uniformly through the space between cathode 51 and anode 59.

It is preferred to concentrate that magnetic flux, which acts to modulate the direction of travel of the individual electron paths, as indicated by line 63, and thereby to modulate the phase of alternating current induced in the anode elements 59, 60, GI and in the anode 62. It is preferred to concentrate that magnetic flux as much as possible in the region directly around the control electrode structure 58. Such concentration of the magnetic flux in the initial part of the path of such an electron beam as is generated in the special discharge devices described herein reduces distortion to a great extent. To increase the magnetic flux in any discharge device of the kinds herein described, tends to bend the path of electrons away from the position it would have in the absence of a deflecting magnetic flux more and more rapidly as the amount of such flux increases. That is, the amount of displacement of the point on the anodes at which an electron impinges increases at a rate greater than proportional to the increase of magnetic flux intensity where the magnetic flux is distributed through a substantial part of the space between the cathode 51 and the tube output anode.

If, on the other hand, the magnetic flux is applied only to the initial part of the path of an electron, the electron is deflected initially and follows a substantially straight line thereafter, with the result that the amount of displacement of the point where the electron impinges on one of the anodes is much more nearly proportional to the intensity of the magnetic flux. This reasoning follows the same line as that set forth with respect to Figure 7 in which it is explained how the action of focusing anodes l and 8 in concentrating the magnetic flux produces this greater proportionality.

It should be noted that the amount of deflection need not be decreased by such concentration of the magnetic flux provided the total amount of the flux is the same.

In Figure 9 there is illustrated an arragnement in which a discharge device similar to that illustrated schematically in Figure 8 is provided with flux concentrating means includingironpole pieces 64 and 65. Although the electrodes illustrated in Figure 9 are substantially shorter in the direction of the axis of the cathode than are those in the device of Figure 8, they are given like reference numerals because their action in producing rotating electron density waves which generate alternating currents in the output anodes is substantially the same. These pole pieces 64 and 65 have cupped faces adjacent the control electrode structure 58 which act to concentrate substantially all of the magnetic flux within or near the cylinder formed by the control electrode structure 58. The electrodes of this device are i i" made short in order that the distance between these cupped faces of the pole pieces 64 and 65 may be kept small with respect to the area of the faces of those pole pieces in order that they shall act efficiently in producing the desired flux concentration.

All of the forms of the special discharge device described herein may be regarded as modifications of a simple form illustrated in Figures 10 and 11. In the device shown schematically in Figure 10, a flat or plane cathode 66 serves as a source of electrons and a control electrode structure 61 lying in a plane parallel to the cathode 66 is arranged to form electrons from the oathode 66 into beams moving linearily across the surface of the cathode 66. First anode elements B8, 69 and 19, corresponding in number to the number of groups of three of the elements of the control electrode structure 61 lie in the path of the electron density wave set up by these electron beams and are spaced apart in the direction of travel of the wave by an amount substantially equal to their length in that direction. A second anode ll parallel with cathode 66 lies beyond the anode elements 68, 69 and 10 and intercepts any electrons which do not impinge upon those first anode elements.

As illustrated in Figure 11, a magnetic field traversing the space between the cathode 66 and the two anodes bends the electron beam in a direction mutually perpendicular to the direction of motion of the electron densit wave and to the direction of motion of individual electrons in the beam, as illustrated by the dash lines 12 and 13 which define the boundaries of one electron beam. If the magnetic field extends in the same direction with the reverse polarity, the bending of the electron beams is opposite to that illustrated. The phase of alternating currents induced by the impingement of electron beams upon the anode elements 58, 69 and 10 or upon the anode H is respectively advanced or retarded in the presence of such magnetic flux.

In Figure 12 an alternative form of the device shown in Figure 8 is illustrated in which like elements are provided with similar reference numerals and in which a somewhat different control electrode structure 14 is provided. This control electrode structure, instead of being composed of substantially round wires, is formed of substantially flat strips of metal with their longest width dimensions lying radially from cathode 51 and with their long dimensions skewed around cathode 51 enough to present a substantially unbroken electrostatic surface to the oathode. These skewed strips aid in causing the electrostatic field pattern which they produce to rotate at uniform velocity, as explained in connection with a possible modification of Figure 1. It is preferred to use such fiat strips in forming a control electrode structure for such a device because the controlling action of the composite control electrode structure so formed is more eflicient in producing a smoothly rotating device a cathode 15 is surrounded by a control electrode structure which includes several rings 16, each of these rings being concentric with cathode I5 and lying in parallel equally spaced planes all perpendicular to the axis of cathode 15. The rings 16 are grouped for multiphase connection and are suitably connected to a source of multiphase voltage so that they cause the electron emission from cathode to be formed into electron beams in disc form as mentioned and so that they cause these electron beams or discs to move linearily from one end of the cathode to the other. Surrounding the control electrode structure which includes the rings 16 is a first anode including anode elements ll, 18, etc. corresponding in number to the number of groups of rings 78 in which each ring is connected with a different phase conductor. Surrounding the anode elements 11, 18, there is a second concentric anode 18 upon which all electrons which pass between the anode element 11, 78, etc. impinge. Since the operation of this device is substantially identical with that of the simple form illustrated in Figure 10, it is not explained in detail. Current flowing axially through cathode 15 produces deflection of the electron beams or discs, thereby to induce an acceleration or deceleration of the longitudinal electron density wave progressing along the path of anode segments I1, 18, etc., as explained later.

In Figure 14 a special form of the discharge device is illustrated which is similar to that shown by Figure 13 except that the control electrode elements and the first anode elements are formed spirally or helically instead of circularly around cathode 80. That is, three helical coils of wire 8|, 82 and 83 are illustrated interwound one with another, the pitch of any one of the helices being three times the distance between adjacent wires in the control electrode structure. The three control elements 8|, 82 and 83 are connected respectively with the three phase conductors of a suitable source of three phase voltage and thereby act to form an electron beam in the shape of a helicoid which is coaxial with the cathode 80 and which moves linearly along it. Outside of the control electrode structure a helical strip 84 of metal is placed concentrically with the cathode 88, the pitch of this helical strip 84 being the same as the pitch of any one of the control elements 8|, 82 and 83 and being the same as that of the helicoidal beam of electrons formed by the control electrode structure. The width of the strip 84 is approximately one-half of the pitch of the helix formed by it. An anode 85 in the shape of a cylinder is placed around the strip 84 concentric with the cathode 88 and collects all electrons from the helicoidal beam which do not impinge upon the strip 84 whih forms the first anode system.

A practical embodiment of the form of the device illustrated schematically in Figure 14 is shown in Figure 15 in which like elements are given the same reference numerals. The cathode 80 may be formed of a metal tube coated with electron emissive material and indirectly heated by current supplied through twisted conductors 86. A disc 8! fastened centrally to one end of cathode 80 supports at its periphery a cylindrical suppressor electrode 88 which lies between the cylindrical outer anode 85 and the helical inner anode electrode 84, and which serves, being maintained by the disc 81 at cathode potential, to prevent the return of electrons from anode 85 to anode electrode 84. At the other end of the suppressor electrode 88 a second disc 89 is connected peripherally, the disc 89 being insulated at its center from the cathode and connected with a small conducting cylinder 90.

A helicoidal electron beam is formed in the device shown in Figure 15 in the same way as that shown in Figure 14 by the application of three phase potentials to the control elements 8|, 82 and 83, and the electron density wave set up by the helicoidal electron beam is caused to advance or to be retarded in its passage along the cathode 80 and across the helical strip 84 by the production of a cylindrical magnetic field around the cathode 80 parallel with the axis of the oathode. This cylindrical magnetic field fiux is produced by the passage of modulating current through the cathode 80 in one direction or the other by means of two conductors 9| connected respectively to the small conducting cylinder and to that end of the cathode 80 nearest the cylinder 98. Current is caused to flow from one of the conductors 9| through cathode 80, disc 81, suppressor electrode 88, disc 89, cylinder 80 and thus back to the other conductor 9| to cause the helicoidal electron beam to be bent in one direction and current is caused to flow reversely through that circuit to cause the electron beam to be bent in the opposite direction whereby phase changes are produced in the anodes 84 and 85.

Although no means is illustrated in connection with Figures 13 and 14 for the production of magnetic flux to cause such advancing or retarding of the electron density wave in those structures, an arrangement such as that illustrated in Figure 15 may be utilized to produce the magnetic fiux lying in a cylinder concentric with the cathodes 15 and 80 respectively.

In connection with the magnetic flux concentrating means illustrated in connection with the device shown in Figure 1 and in connection with Figure 9, these flux concentrating means can be arranged to reduce residual non-linearity which remains even when such fiux concentrating means is used. Even when such a flux concentrating arrangement, as shown in one of these figures, is utilized, magnetic electron deflection occurs at some distance from the center of the electron discharge device and furthermore occurs over a substantial length of the path traversed by individual electrons, and accordingly, the displacement of the point where the electrons impinge on the respective anodes increases at a rate somewhat greater than proportional to the increase of magnetic flux intensity. By causing the magnetic flux intensity to increase at a rate correspondingly less than proportional to the increase of modulating current which generates the magnetic flux, by selecting a proper ferromagnetic material from which the fiux concentrating means are fashioned, and by properly dimensioning the flux concentrating means, an amount of magnetic saturation can be caused to occur in the ferromagnetic material which will substantially ofiset this residual non-linearity.

This residual non-linearity may also be corrected by other means, one of which is described hereinafter, which cause the rate of increase of modulating current in the coil which produces the magnetic flux to be less than proportional to the rate of increase of intensity of the modulating signal potential.

In Figure 16 there is shown the circuit diagram of a radio transmitter arranged to transmit a carrier wave whose frequency is modulated in accordance with a modulating signal from a microphone 92. This type of transmitter is particularly useful in point to point communication because of its simplicity and the small number of discharge devices utilized in it, which is made possible by the utilization of the discharge device 93 which may, for example, be like the device illustrated in Figure 1. In this transmitter certain measures are taken to reduce the non-linearity heretofore described, but certain of the measurs which are possible if it be desired to attain maximum linearity have been dispensed with in order to make the number of discharge devices as small as possible.

In this transmitter a carrier wave is generated in an oscillating circuit including an electron discharge device 94 and a piezo electric frequency determining element 95. The carrier wave generated in the device 94 is impressed through a phase splitting network 96 upon the three phase control electrodes 91, 98 and 99 of the device 93, in which, as explained previously, an electron density wave is caused to move alternately at carrier frequency across the first anode I and the second anode I 0| of the device 93. Signals from the microphone 92 are amplified through an electron discharge amplifying device I02 and are then impressed upon a magnetic flux producing coil I03, the flux from which acts in the space between cathode I04 and anode I00 of device 93 to cause phase shift, either advancing or retarding the passageof the electron density wave as it moves alternately across the anodes I00 and IM of the device 93.

The amplifying device I02 has a substantially constant voltage output characteristic, in the presence of constant input voltages of varying frequency, and consequently by reason of the inductance of coil I03 current flowing through the coil and magnetic flux produced by it within the device 93 are substantially inversely proportional to frequency. Correspondingly, the phase shift produced as a result upon the anode IOI of device 93 is substantially inversely proportional to the frequency of signals from the microphone 92, which means that the modulation of the phase of the carrier wave current in the anode IOI is such that the frequency of that carrier wave current is modulated substantially proportional to instantaneous modulated signal voltage from the microphone 92 regardless of the frequency of that voltage. It is therefore a frequency modulated carrier wave which is developed upon the anode IOI of device 93.

This frequency modulated carrier wave is impressed upon the control electrode I05 of an electron discharge amplifying device I08, which is arranged to produce a frequency multiplication of, for example, four times the frequency of the carrier wave impressed upon its control electrode I05. This multiplication of frequency in the device I06 serves two purposes. In the first place it increases the amount of frequency modulation of the carrier wave to an amount such that the frequency shift of the carrier wave in relation to the maximum frequency of modulating signals from the microphone 92 is sumcient to provide substantially noise free reception of the signals in a suitable frequency modulation receiver which incorporates an efiicient limiter. In the second place it makes possible the transmission of a high frequency carrier wave, for example, at 40 megacycles, while operating the discharge device 94 and the associated piezo electric crystal 95 at a much lower frequency where frequency stability id under varying temperature conditions and the like can be more readily attained than at higher frequencies.

The high frequency carrier wave, modulated in frequency in substantial amount by alternating signal potentials from the microphone 92, after it appears upon the anode I0'I of discharge device I06 is impressed on the control electrode I08 of a relatively high power electron discharge amplifying device I09, from the anode IIO of which the frequency modulated high frequency carrier wave is impressed upon a radiating element III which may, for example, at high frequencies take the form of a dipole or of a relatively short rod antenna working against a counterpoise.

The oscillator including the device 94 is of conventional form in which the two electrodes of the piezo electric frequency determining element are respectively connected to the control electrode H2 and the grounded cathode II3. A grid leak resistance I I4 is also connected between the control electrode H2 and the cathode H3 and the anode II5 of the device 94 is connected through a tuned circuit including an inductance H6 and a condenser I I I in parallel with each other to the positive terminal of a source II8 of suitable operating potential for the device 94, the negative terminal of the source IIB being grounded. A by-pass condenser I I9 is connected between ground and that end of the tuned circuit II6, I I1 opposite to the anode I I5. The tuned circuit I I6, I I1 is resonant at the fundamental frequency or some mechanical harmonic frequency of the piezo electric device 95 and the oscillator maintains oscillations of highly constant frequency by reason of voltage feed-back through inter-electrode capacity between anode H5 and control electrode H2 and by reason of the well known large frequency stability of piezo electric frequency determining elements such as the device 95.

The inductance coil I I6 is magnetically coupled with an inductance I20 whose center tap is connected to ground through a by-passing condenser I 2I with the result that balanced highly stable carrier voltages are induced in coil I20. The phase splitting network 96 includes a bridge circuit in which an inductance I22 and a resistance I23 are connected serially between the terminals of coil I 20 and in which a condenser I24 and a resistance I25 are also connected serially between the terminals of coil I 20. The inductance I22 and the condenser I24 are connected to the same terminal of the coil I20 and the resistances I23 and I25 are connected to the opposite terminal. A resistance I26 is connected between a control element 9'! of the device 93 and that terminal of the coil I20 to which inductance I 22 and condenser I24 are connected. The control element 98 of the device 93 is connected through a condenser I2! to a point in the bridge circuit between inductance I22 and resistance I23, and a grid leak resistance I28 is connected in shunt with condenser I2'I in order to maintain the control element 98 at substantially the same potential as the control elements 97 and 99. The resistance I28 should be large compared with the reactance of the condenser I2I at carrier wave frequency. An inductance I29 is connected between control element 99 of device 93 and a point in the bridge circuit between condenser I24 and resistance I25.

This phase splitting network 95 is arranged to produce carrier wave voltages on the control elements 91, 98 and 99, the phases of which voltages are equally displaced one from the other by so that the voltages appearing on these three control elements form what is commonly termed a three phase voltage. The network also has the characteristic that it has the same output impedance measured at any one of the three control elements 91, 98 and 99 and impresses on those three control elements voltages of equal intensity. It should be understood that it is within the scope of my invention to use more than three electrodes, and to impress on such electrodes whether they be three or more any kind of multi-phase voltage whose individual phases are correlated with the physical positions of the control elements with respect to one another and with respect to the cathode I04 so as to form a uniform velocity electron density wave. For example, one or two of the control elements 91, 98 and 99 might be physically displaced from the positions illustrated in Figures 1 and 2 provided the relative phases of the voltages impressed on them are correspondingly changed.

In order to have such characteristics the phase splitting network 96 must have certain impedance relations between its elements. Resistances I 23 and I25 must be equal and they must be one-third greater than resistance I26. The reactance at the carrier wave frequency in question of inductance I22 must be equal to the reactance at that frequency of condenser I24 and must also be equal to resistance I23 multiplied by the squareroot of 3. The reactance at the carrier wave frequency in question of inductance I29 must be equal to the reactance at that frequency of the condenser I21 and must also be equal to the resistance I23 multiplied by one-fourth of the square-root of three.

By way of a practical example of such a network the seven elements may be constructed to have the following impedances. Inductance I22 may be of 588 ohms, resistance I23 of 340 ohms, condenser I24 of 588 ohms, resistance I25 of 340 ohms, resistance I26 of 255 ohms, condenser I21 of 147 ohms, and inductance I29 of 147 ohms.

Operating current and bias potentials are supplied to the device 93 as follows. The first anode I is connected to the positive terminal of source H8 and the anode IOI is connected to that same positive terminal through a tuned output circuit including an inductance I30 and a condenser I3I in parallel relation. A suppressor electrode I32 within the device 93 is connected with the cathode I04. Four resistances I33, I34, I35 and I36 are connected between ground and the positive terminal of source H8 and a first focusing anode I31 in device 93 is connected to a point between resistances I33 and I34 and is by-passed to ground through a condenser I38. A second focusing anode I39 in the device 93 is connected to a point of higher positive potential between resistances I35 and I36 and is by-passed to ground through a condenser I40. The center tap of the coil I 20 is connected to a point between resistances I34 and I35 whereby the control elements 91, 98 and 99 are maintained at a potential positive with respect to cathode I04 and intermediate the potentials of the focusing electrodes I31 and I 39.

Modulatin signals from the microphone 92, which as illustrated may be a carbon microphone, are impressed serially across a source I4l of biasing potential for the carbon microphone, the primary winding I42 of a voltage step-up transformer and a switch I43. The secondary I44 of that transformer is connected between the control electrode I45 of the device I02 and ground, the cathode I46 of the device I02 being connected 18 to ground through a biasing resistance I41. This biasing resistance I41 is only sufilciently large to provide proper bias potential between the control electrode I45 and cathode I46 and a small amount of degeneration to improve the linearity of amplification of the device I02 and it is not large enough to introduce enough degeneration to produce any substantial change in the constant voltage characteristic of the output circuit of device I02. The anode I48 of device I02 is connected through a resistance I49 to the positive terminal of source H8 and the anode I48 is also connected through a coupling condenser I50 to one terminal of the coil I03 of which the other terminal is grounded.

As mentioned briefly above signals from microphone 92 are amplified through the device I02,- connected as described to act as a power amplifier, and are caused by the coil I03 to produce magnetic flux in device 93 whose intensity is substantially inversely proportional to signal frequency. This relation between flux intensity and instantaneous signal voltage cannot be maintained at all signal frequencies from zero to some high frequency such as 10,000 cycles, but for pointto point communication work in which most of the intelligence is speech, such a wide frequency range is not necessary or desirable. Actually it is usually necessary to transmit signal frequencies within a range for example between 200 and 3000 cycles and within that range it is not difiicult to maintain substantially the desired relation between the magnetic flux intensity and instantaneous signal voltage. At the lower signal frequencies there is a tendency for the amplifier including device I02 to act less like a power-amplifier so that the current in coil I03 at such lower frequencies may not be quite as great as it should be and consequently the phase shift in carrier wave currents in the anode IOI may be somewhat less than desired. This means that the frequency shift of the carrier wave in response to such lower signal frequencies is somewhat less than linearly proportional to instantaneous signal voltage, which in turn means that some higher signal frequencies are transmitted in greater intensity than signal voltages of lower frequency. This may not be undesirable and may in fact lead to somewhat better speech understanding in the system.

The non-linearity between instantaneous magnetic flux intensity applied by coil I03 to the device 93 and the consequent phase shift of carrier wave current in the anode II, as discussed previously, may be corrected in several ways. For example, ferromagnetic material may be utilized as described in connection with Figure l to produce a desired amount of flux saturation in order to correct such non-linearity. Alternatively the amplifier including the device I02 may be arranged so that its gain is reduced in proper amount in response to increasing instantaneous signal voltage in order to produce a similar fiattening of the tops of half cycles of the signal voltage.

Frequency modulated carrier wave voltages appearing across the tuned circuit I30, I3I are impressed between the control electrode I05 and the grounded cathode I5I of device I06 through a coupling condenser I52. A suitable grid leak resistance I53 is connected between the control electrode I05 and cathode I 5I and is arranged with such resistance in relation to the intensity of the carrier wave so as to produce a bias potential on control electrode I05 sufiiciently large to cause device I06 to operate in suitable manner for frequency multiplication. The anode I01 of device I06 is connected through a tuned circuit including an inductance I54 and a condenser I55, in parallel relation, and then through a decoupling resistance I56 to the positive terminal of source I'IB, a point between resistance I56 and the tuned circuit I54, I55 being by-passed to ground for carrier frequency currents through a by-passing condenser I51. The tuned circuit I54, I55 is resonant at a suitable multiple of the frequency of the carrier wave impressed on control electrode I so that the device I06 operates efiiciently as a frequency multiplier.

Such higher frequency carrier wave voltages appearing across the tuned circuit I54, I55 are impressed through a coupling condenser I58 between the control electrode I08 and the grounded cathode I59 of the power amplifier I09. A suitable grid leak resistance I60 is connected between the control electrode I08 and cathode I59 and is sufficiently large to provide bias potential therebetween so that device I09 operates efficiently as a power amplifier. For example, the bias potential between control electrode I08 and cathode I59 may be sufiicient to cause what is known as Class C operation in which discharge current in the device I09 is prevented at all times except during short intervals in alternate half cycles of the carrier wave. The screen electrode I6I of the device I09 is by-passed for currents of carrier frequency to ground through a by-passing condenser I62 and. is connected to the positive terminal of a source I63 of potential of which the negative terminal is grounded. The anode I I0 of the device I 09 is connected through a tuned circuit including an inductance I64 and a condenser I65 in parallel relation to the screen electrode I6I. The inductance coil I64 is electromagnetically coupled with an inductance I66 to the ends of which are connected the radiating element or elements I, suitably arranged to radiate properly at the frequency of a carrier wave from device I09 to which the tuned circuit I64, I65 is resonant.

The operation of the phase splitting network 96 is as follows: control element 91 is excited in phase through resistance I26 with carrier wave voltage at the upper terminal of coil I20. A lagging current flows between the terminals of coil I20 through inductance I22 and resistance I23 and produces a voltage through condenser I21 on control element 98 which lags by 120 the carrier voltage on control element 91. It is the function of condenser I21 to resonate at carrier frequency with the inductance in the remainder of the circuit between control element 98 and ground, so that the impedance of that entire circuit appears resistive, as does the impedance of the circuit between control element 91 and ground. Similarly, a leading current flows between the terminals of coil I 20 through condenser I24 and resistance I25 and a leading voltage is impressed through inductance I29 on control element 99, that voltage leading the voltage on control element 91 by 120. The inductance I29 resonates at carrier frequency with capacity in the remainder of the circuit between control element 99 and. ground so that that whole circuit appears resistive at the control element 99 at carrier frequency.

This phase splitting network 96 is arranged in this fashion so that, when loads are applied to its output terminals, as by the flow of charging current in the control elements 91, 98 and 99,

the symmetrical three phase distribution of its three phase voltage output is not disturbed. Without the special measures taken in the network 96 to prevent such loading efiects, the equally phased output voltage of the network would be seriously disturbed, even if loads taken from the network were symmetrical, and these resulting asymmetries in the multiphase voltage output of the network 96 might become so large as to reverse phase rotation which would obviously cause the system to become inoperative. By providing the network 96 with its spe-- cial characteristics to insure the impression, of voltages equally displaced in phase on control elements 91, 9B and 99, and asymmetry in those voltages which might be introduced by loading caused by current flow in the control elements is entirely avoided.

While, in the circuit arrangement of Figure 16, the first focusing anode I3! is provided with a suitable positive bias potential with respect to cathode I04, it can be made to operate properly if it is maintained at cathode potential. For that purpose it may be connected directly with cathode I04 outside of the envelope of device 93, or preferably inside of that envelope.

The discharge device 93, as described for example in Figure 1, does not produce a sinusoidal current flow in the anodes I00 and IOI. While special forms of the discharge device may be constructed to produce sinusoidal current variations in those anodes, good output for the discharge device can be obtained without that expedient. In fact, the device 93, where its output current is not sinusoidal, can be used as the frequency multiplier by the simple expedient of making the tuned circuit I30, I 3I resonant at a frequency which is a multiple of the frequency of the carrier Wave impressed on the network 96. For example, the usual type of wave form of the output current of device 93 has a substantial third harmonic content.

It should be emphasized that the coil I03 in connection with this special discharge device 93 simultaneously performs at least two functions which have heretofore necessarily been performed by entirely separate devices. The coil I03 with the discharge device 93 modulates the phase of a carrier wave in accordance with signal potentials from discharge device I02 and simultaneously, by virtue of the fact that it is an inductance, produces proportionately less phase modulating magnetic flux in response to signal voltages of high frequency than of low frequency, so that the type of phase modulation of the carrier wave which is produced is in fact frequency modulation, the frequency shifts of the carrier wave being substantially linearly proportional to instantaneous signal potential at any signal frequency.

It should also be kept clearly in mind that, as explained before, to operate in this fashion the coil I03 must be supplied with signal voltage which is at all times linearly proportional to instantaneous signal voltage produced by microphone 92. In order to assure this, the power amplifier including discharge device I02 must have an output circuit which, measured at the coil I03, has as low an impedance as possible. A satisfactorily low impedance amplifier can be provided by making resistance I 49 relatively small and by utilizing as a discharge device I02 a device of the type termed a power amplifier in which relatively large space current may flow and in which the control electrode I is usually of relatively large mesh spaced at relatively large distance from the cathode I46. Provided resistance I49 be made sufliciently small, the output impedance of the amplifier can-be made as low as desired so long as the device I02 is capable of generating the necessary signal potential across the small resistance I49.

Good operation of the system results if the output impedance of the amplifier including device I02 and resistance I49 is substantially resistive and equal to the impedance of coil I03 at a frequency near the lowest frequency within the band of frequencies of the signals to be transmitted. If the internal anode resistance of the device I02 is large with respect to the magnitude of resistance I49, the resistance I49 and coil I03 may be made to have substantially equal impedances at the lowest signal frequency to be transmitted and satisfactory results may be obtained.

If the output resistance of the amplifier including device I02 and resistance I49 is substantially equal to the impedance of coil I03 at a frequency substantially higher than the lowest signal frequency to be transmitted, there is less frequency shift of the carrier wave in response to the same instantaneous signal potential at frequencies below that frequency of equality than at higher frequencies. Transmission of frequency modulated carrier waves is commonly carried out with what is termed pre-emphasis, in which the frequency shift of the carrier wave is intentionally made to be greater in response to instantaneous signal potential at high signal frequencies than at low, for the purpose of reducing the effect of undesired noise and static voltages in the system. In view of the similarity of such pre-emphasis with the effect obtained in the present system when the amplifier output resistance is equal to the reactance of coil I03 at a frequency higher than the lowest signal frequency to be transmitted, that efifect is herein termed pre-emphasis. The general statement may be made that, where such pre-emphasis is desired, the impedance of the signal amplifier including device I02 and resistance I 49 should be substantially resistive and equal to the impedance of coil I03 at a frequency within the band of frequencies of the signal from the signal amplifier so that, above that frequency of equality, current in the coil I03 is substantially inversely proportional to signal frequency with a constant signal intensity and lags the signal voltage, while at frequencies below that frequency of equality current in the coil I03 is substantially independent of signal frequency and is substantially in phase with signal voltage from the signal amplifier. Under those conditions the signal amplifier and the coil I03 should be so arranged that the frequency of equality is at least three times as great as that frequency at which with substantially all the frequency modulation of the carrier wave for which the transmitter is designed, the non-linearity between flux produced by current in the coil I03 and the phase shift which results in the carrier wave in the output circuit of device 93 becomes greater than the non-linearity for which the transmitter is to be designed.

In Figure 17 a transmitter circuit is illustrated which is especially useful for the transmission of carrier waves frequency modulated in accordance with high fidelity, audio signals such as are transmitted for broadcast purposes. Although, in general, this type of transmitter includes elements analogous to those described in connection with Figure 16, each of these elements differs in certain respects in order to obtain the results desired of a high fidelity broadcast transmitter of the frequency modulation type.

The oscillation generator includes a frequency determining device I61 connected between the anode I68 and the control electrode I69 of a pentode type electron discharge device I10. A resistance IN is connected between the control electrode I69 and the grounded cathode I12 for the passage of grid current therebetween to provide a suitable operating bias potential. The anode I68 is connected through a tuned circuit including an inductance I13 and a condenser I14, in parallel relation, and then through a resistance I15 to the positive terminal of a source I16 of operating potential, the negative terminal of which is grounded. The screen electrode I11 is also connected through resistance I15 to the positive terminal of source I16 and is connected to ground through a by-passing condenser I18.

This oscillation generator operates by reason of voltage feedback from anode I68 to control electrode I69 through the piezo electric device I61, the tuned circuit I13, I14 being resonant at a resonant frequency of the device I61. It is convenient to make the oscillator including device I10 operate at a relatively low frequency, for example, in the order of one-half megacycle or less, because at such frequencies quartz crystals can be constructed and arranged in such oscillators to provide extremely high frequency stability under changing conditions encountered in the use of the apparatus.

A carrier wave generated by the oscillator is impressed on the device I19, which is one of the special forms of electron discharge device heretofore described and which has its anodes I80 and I8I especially arranged for operation in push-pull relation. To this end, the inductance I13 is magnetically coupled with an inductance I82 whose center tap is by-passed to ground through a bypassing condenser I83. Carrier wave voltages induced in coil I82 are in balanced relation with respect to ground and are transferred through a simple form of phase splitting network to three control elements I84, I and I86. Control element I84 is connected directly with the upper terminal of coil I82. A resistance I81 and a condenser I 88 are connected serially between the terminals of coil I82 and a second condenser I 89, and second resistance I are also connected serially between the terminals of coil I82, resistance I81 and condenser I 89 being connected to the same terminal. Control element I85 is connected to a point between condenser I89 and resistance I90, and control element I86 is connected to a point between resistance I81 and condenser I88.

Leading current flows between the terminals of coil I82 through resistance I81 and condenser I88, and by adjusting relatively to each other the reactance of condenser I88 and the resistance I81 this leading current can be caused to produce a voltage drop across the resistance I81 such that the voltage on control electrode I86 lags the voltage on control electrode I84 by one-third of a cycle or That is, at the frequency of the carrier wave in question the resistance I81 should be greater than the reactance of condenser I 88 by a multiplying factor equal to the square root of 3. Current flowing between the terminals of coil I82 through condenser I89 and resistance I90 is also leading in larger amounts than current through resistance I81, and the resistance I90 and the reactance of condenser I89 should be adjusted so that the voltage on control electrode I85 leads the 23 voltage on control electrode I84 by one-third cycle or 120. This will be the case if the reactance of condenser I89 at the carrier frequency in ques tion is greater than resistance I90 by a multiplying factor equal to the square root of 3.

The control electrodes I84, I85 and I86 are maintained at a suitable positive potential with respect to the grounded cathode I9I of device I19 by means of a connection between the center tap of coil I82 to a point between resistances I92 and I93 of a potential divider including resistances I94, I92, I93, I95 and I96 connected serially in named order from ground to the positive terminal of source I16.

Because these control elements I84, I85 and I86 are maintained at a positive potential with respect to cathode I9I, they inevitably have space current from cathode I9I flowing through them, and consequently impose some load on the phase splitting network I81, I88, I89 and I90. Such load imposed on that network tends to cause the otherwise accurately evenly phased threephase voltages produced by the network to be changed in phase with respect to one another with the consequence that the moving electrostatic field may be somewhat distorted. This distortion can be compensated in several ways although in practical arrangements it is usually necessary only to make the impedances of the elements in the phase splitting network sufliciently low that the undesired phase change caused by loading is within tolerable limits, but not so low as to reduce undesirably the driving voltage available from the oscillator including device I'I0. If it be desired the physical positioning of the control elements I84, I85 and I86 may be made slightly asymmetrical in an amount just sufficient to compensate for the asymmetry of the three-phase voltage produced by the network so that a uniformly moving electrostatic field is produced. Alternatively, the impedances of the elements of the network may be adjustedunder load to produce a substantially symmetrical threephase voltage, and if it be necessary to obtain the desired symmetry the phase shifting network such as that illustrated in Figure 16 may be utilized.

The first focusing anode I91 of the device I19 is connected to a point between resistances I92 and I94 of the potential divider and is by-passed to ground for currents of carrier frequency through a by-passing condenser I98. As explained previously, the anode I91 may be connected to cathode I9I if it is properly constructed for good focusing at the cathode potential. The

second focusing anode I99 is connected to a point between resistances I93 and I95 and is by-passed to ground for currents of carrier frequency through a by-passing condenser 200. The output electrodes I80 and I8I of the device I19 are connected to the opposite terminals of a tuned circuit including an inductance 20I and a condenser 202 in parallel relation, the center tap of the inductance 20I being connected to a point between resistances I95 and I96 and being by-passed to ground for currents of carrier frequency through a by-passing condenser 203.

As explained previously in connection with the discharge device 93 of Figure 16, the discharge device I19 operates to move a uniform velocity electron density wave across the anode path, thereby producing a carrier wave potential across the tuned circuit 20I, 202, which is resonant at the frequency of the carrier wave generated by the oscillator I19 or at a multiple thereof.

Modulating signals produced by a microphone 204 are amplified through a suitable program amplifier 205, of which the output circuit has three terminals including a grounded center terminal and two other terminals between which a voltage balanced with respect to ground exists. These two balanced voltage terminals of the amplifier 205 are connected respectively through filter resistances 206 and 201 to the control electrodes 208 and 209 of a pair of power amplifier discharge devices 2I0 and 2 connected in balanced relation. A filter condenser 2I2 and re sistance 2I3 are connected serially between the control electrodes 208 and 209 and, together with the filter resistances 206 and 201, alter the frequency response of the signal amplifying system in a desired manner by reducing in an amount determined by the relative impedances of the filter elements the high frequency components of the signal. The cathodes 2I4 and 2I5 of the devices 2I0 and 2 are connected together through a balancing resistance 2I6, whose cen-- ter tap is connected through a biasing resistance 2I1 to ground. The screen electrodes 2I8 of the devices 2I0 and 2 are connected to the positive terminal of the source I16 and the two anodes 2I9 and 220 are connected together through a magnetic flux producing coil 22I which is arranged with respect to the device I19 to produce magnetic flux varying in accordance with some function of signal potential in the space between cathode I! and the output electrodes I80 and I8I, in a fashion similar to the operation of coil I03 with device 93 of Figure 16. A resistance 222, an inductance 223, and a resistance 224 are connected serially in the named order between the anodes 2I9 and 220, and the center tap of inductance 223 is connected with the positive terminal of source I16.

Although the devices 2I0 and 2 are of the type termed power amplifiers, by reason of the fact that they have screen electrodes 2I8 the internal anode resistance is relatively high and consequently the resistances 222 and 224 are made small for reasons set forth in connection with resistance I49 of Figure 16. Similar considerations apply to the relation between the magnitudes of resistances 222 and 224 and the inductance of coil 22I as were set forth with respect to resistance I49 and coil I03.

The inclusion of coil 223 in series with resistances 222 and 224 provides pre-emphasis in that the inductance of coil 223 is related to resistances 222- and 224' so that the impedance of those elements taken together increases at a predetermined rate as signal frequency increases above a frequency at which the reactance of coil 223 is equal to the combined resistance of resistances 222 and 224. The frequency at which this equality exists is generally in the upper portion of the band of frequencies of the signal to be trans mitted, and above that frequency an amount of pre-emphasis exists which is determined by the relation between the inductance of coil 223 and resistances 222 and 224. That is, the larger the inductance of coil 223 the more rapidly signal voltage between anodes 2I9 and 220 increases with a constant input signal voltage of increasing frequency.

The system so described produces across the tuned circuit 20I, 202 a carrier wave whose frequency is modulated in accordance with the instantaneous intensity of signal potential regardless of signal frequency except for the pre-emphasis described.

This frequency modulated carrier wave voltage across coil 20l appears across an inductance coil 225 with which it is magnetically coupled, and. a condenser 226 is connected in shunt with coil 225 to form a tuned circuit resonant at the same frequency as circuit 20l, 202. Voltage across the tuned circuit 225, 226 is amplified and its frequency is multiplied a suitable amount in a frequency multiplier 221. The frequency multiplication may be in the order of one hundred or more times in order to obtain the desired amount of carrier Wave frequency shift in response to signal potentials, which frequency shift for broadcast purposes is desirably several times greater than the highest frequency in the signal to be transmitted.

The output terminals of the frequency multiplier 221 are connected respectively with the control electrode 228 and the negative terminal of a source 229 of suitable biasing potential for the control electrode 220 of a high power electron discharge amplifier 230, the cathode 23l of which is grounded and is connected to the positive terminal of source 229. The anode 232 of device 230 is connected to one terminal of a tuned circuit including an inductance 233 and a condenser 234 in parallel relation, and the other terminal of the tuned circuit is connected to the positive terminal of source 235 of high potential suitable for the operation of the high power amplifier 230. The screen electrode 230 of the device 230 is connected to a tapped potential point of the source 235 to maintain the screen electrode 230 at a suitable positive potential with respect to cathode 23l, the negative terminal of source 235 being grounded. A by-passing condenser 23! is con-- nected between screen electrode 236 and cathode 23l.

The tuned circuit 233, 234 is resonant at the frequency of the carrier wave impressed on control electrode 228 by frequency multiplier 22! and the inductance 233 is magnetically coupled with an inductance 238 which is connected with the radiating system 239 arranged to radiate the high power frequency modulated carrier wave from the device 230'.

Although the transmitter of Figure 17 is described as having the frequency multiplier 22'! arranged to multiply the frequency of the carrier wave, whose frequency is modulated by device I19, by one hundred or more times, this is not to be understood as meaning that this transmitter has any such large number of discharge devices as are necessary in present day frequency modulation transmitters of the phase modulation type.

In such transmitters where the maximum phase shift attainable is less than one-half cycle and is not usually more than one-quarter cycle, a much greater amount of frequency multiplication is necessary since in the present system a phase shift of as much as four cycles or more may be readily attained with high linearity. The advantage given by such greater available initial phase shift does not lie only in a substantial reduction in number of discharge devices necessary in the frequency multiplier 221, since it is actually of greater importance that, with such a much greater phase shift a large reduction in noise potentials and other undesired voltages is obtained, while retaining the advantage of quartz crystal control of the carrier wave center frequency and at the same time attaining to a high degree proportionality between instantaneous signal potential and frequency shift of the carrier wave.

With'moderately careful construction of the device I19 and with the provision of adequately filtered power supplies the system produces a frequency modulated carrier wave which is substantially unmodulated in amplitude.

In the transmitter illustrated in Figure 16 several alternative ways of maintaining this linearity were described. In the transmitter of Figure 17 magnetic saturation is not utilized as in Figure 16 and it is instead preferred to arrange the balanced amplifiers 2l0 and 2 to cause signal voltage appearing across coil 22! to increase at a rate less than proportional to the increase of instantaneous signal potential on control electrodes 208 and 209. This is readily accomplished in such a balanced amplifier by impressing suitable bias potential on the control electrodes 208 and 209 so that, upon an instantaneous increase in signal potential upon either of the control electrodes 208 or 209 the increase in voltage across coil 22l is somewhat less than proportional by reason of the fact that such power amplifier devices have an initially curved grid voltage plate current characteristic. By adjustment of the tap on resistance 216 this characteristic of the devices 2| 0 and 2!! can be nicely adjusted to be symmetrical with reference to zero signal voltage and with reference to zero current in coil 22 l While particular embodiments of the present invention has been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from this invention in its broader aspects, and, therefore, the aim of the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of this invention.

I claim:

1. An electron discharge device having an envelope, a cathode, at least three control electrodes, at least one other electrode having a plurality of spaced conducting areas, each of said control electrodes having a plurality of electron controlling areas regularly spaced from each other and effective upon application of multiphase potentials thereto to cause an electron density Wave to progress at uniform velocity successively and continuously over said conducting areas, and a magnetic flux carrying member having a flux emitting end positioned adjacent the space between said cathode and said other electrode, said member being oriented to direct flux through said space substantially at right angles both to the motion of said wave and to the paths of individual electrons flowing from said cathode to said other electrode.

2. An electron discharge device having an envelope, a cathode, a plurality of control electrodes, an anode having a plurality of electron receiving areas, an electron collecting electrode adjacent said anode, said control electrodes comprising electron controlling areas interconnected in a plurality of electrically separate groups in interlaced fashion and being spaced to cause an electron density wave to progress at uniform velocity successively and continuously across said areas upon application of multiphase potentials to said groups of interconnected control electrodes, the number of said receiving areas bearing an integra1 relation to the number of said controlling areas in each group, and a magnetic flux carrying member having a flux emitting end positioned adjacent the space between said cathode and said anode, said member being oriented to direct flux through said space substantially at right angles both to 27 the motion of said wave and to the paths of individual electrons flowing from said cathode to said anode.

3. An electron discharge device having an envelope, a cathode, an anode, a plurality of spaced electron controlling areas, said anode comprising a plurality of spaced electron receiving areas, said electron controlling areas being interconnected into groups such that upon traversing the region between said cathode and said anode in one direction controlling areas of said groups are encountered recurrently in the same cyclic order, said controlling areas being spaced to cause an electron density wave to progress at uniform velocity successively and continuously across said receiving areas in response to the application of multiphase voltages to said groups of controlling areas, and a magnetic flux carrying member having a flux emitting end positioned adjacent the space between said cathode and said anode, said member being oriented to direct flux through said space substantially at right angles both to the motion of said wave and to the paths of individual electrons flowing from said cathode to said anode.

4. An electron discharge device having an envelope, a cathode, an anode, an electrode structure positioned between said anode and said cathode and effective upon connection to a source of multiphase potentials to cause an electron density wave to move at uniform velocity over said anode, and a magnetic flux carrying member having a flux emitting end positioned in close proximity to said cathode and oriented to direct flux through the space between said anode and said cathode in a direction substantially at right angles both to the motion of said wave and to the paths of individual electrons flowing from said cathode to said anode, the motion of said wave being accelerated or decelerated substantially linearly in response to the flux flowing from said flux emitting end by reason of the proximity of said end to said cathode.

5. An electron discharge device comprising a linear cathode, a plurality of helical control electrodes surrounding said cathode and concentric therewith, the helix of each of said control electrodes having a predetermined pitch between its adjacent turns, said electrodes being wound together around said cathode with their adjacent turns spaced apart by substantially equal distances whereby multiphase symmetrical potentials impressed on said control electrodes create a substantially uniformly moving electrostatic field pattern therearound, a first anode comprising a conductive strip wound helically and concentrically around said control electrodes and having a pitch between its adjacent turns differing in not more than a small amount from the pitch of one of said control electrodes, a second anode arranged around said first anode to collect electrons from said cathode which pass said first anode, whereby in the presence of said potentials on said control electrodes an electron density wave is caused continuously to traverse at uniform velocity in an axial direction said first and second anodes, said cathode including a conductive tube having electron emissive material deposited on the outer surface thereof, said tube forming a part of a signal circuit, said circuit having electrical terminals at opposite ends thereof to permit application of signal modulating currents therethrough, said circuit being effective upon connection to a source of electric current to produce a cylindrical magnetic field through- 28 out the region of flow of electrons from said cathode to said first anode, whereby the progress across said first and second anodes by said. electron density wave is accelerated or decelerated, depending upon the polarity of the signal modulating current flowing in said signal circuit.

6. An electron discharge device including a cathode, a plurality of electrodes spaced with relation to each other and to said cathode to cause an electron density wave to progress at uniform velocity continuously along a path in response to excitation of said electrodes by multiphase potentials, an anode having segments lying in spaced relation along said path, and a magnetic flux carrying member having a flux emitting end positioned adjacent the space between said cathode and said anode, said member being oriented to direct flux through said space substantially at right angles both to the motion of said wave and to the paths of individual electrons flowing from said cathode to said anode.

7. An electron discharge device including a cathode, a plurality of anode segments mounted in spaced relation along a path, a plurality of control electrodes mounted between said cathode and said anode and positioned to form a beam of electrons and to alter periodically the electron distribution in such beam thereby to cause an electron density wave to progress at uniform velocity continuously and recurrently along said path upon connection of said control electrodes to a source of multiphase potentials, and magnetic flux directing elements mounted in proximity to said control electrodes and adjacent said beam on opposite sides thereof to concentrate magnetic flux near said cathode in a direction substantially normal both to said path and to the paths of individual electrons flowing from said cathode to said segmented anode.

8. An electron discharge device including a cathode, a segmented anode, focusing electrodes mounted in proximity to said cathode intermediate said cathode and said anode, said focusing electrodes being eifective upon application of operating potentials thereto to focus electrons from said cathode onto said segmented anode, a plurality of control electrodes mounted in spaced relation to each other adjacent the concentration of electrons produced by such focusing, said control electrodes being effective upon connection to a source of multiphase potentials to produce a moving pattern in the electrostatic field induced adjacent said control electrodes, said electron cencentration being subject to such field by reason of the close proximity of said control electrodes to said electron concentration, whereby an electron density wave is caused to pass at uniform velocity over said segmented anode, and a magnetic flux carrying member having a flux emitting end positioned adjacent the space between said cathode and said anode, said member being oriented to direct flux through said space substantially at right angles both to the motion of said wave and to the paths of individual electrons from said cathode to said anode.

9. An electron discharge device including a cathode having an electron emissive area, focusing electrodes mounted in coaxial relation to said cathode adjacent opposite extremities of the emissive area thereof to concentrate the electrons emitted from said area into a disc Of electrons upon application of operating potentials to said focusing electrodes, a segmented anode mounted in coaxial relationship to said cathode and having a radius substantially equal to the radius of said disc, at least one control electrode structure coaxial with said cathode and adjacent said disc of electrons, said structure including a plurality of control elements regularly spaced from each other and from said cathode and skewed to present a substantially unbroken control surface to said disc, the spacing of said elements being such that upon application of multiphase operating potentials thereto there is produced regularly recurrent deflection of the electrons in said disc in a direction normal to said disc in regions adjacent each of said control elements thereby to cause an electron density wave to pass at uniform velocity continuously and recurrently over said segmented anode, and a magnetic flux carrying member having a flux emitting end positioned adjacent the space between said cathode and said anode, said member being oriented to direct flux through said space substantially at right angles both to the motion of said wave and to the paths of individual electrons from said cathode to said anode.

10. An electron discharge device including a cathode having an electron emissive area, a segmented anode mounted in coaxial relationship to said cathode, focusing electrodes mounted in coaxial relation to said cathode adjacent opposite extremities of the emissive area thereof to concentrate electrons emitted from said area into a disc of electrons upon application of operating potentials to said electrodes, a pair of control electrode structures mounted coaxially with respect to said cathode adjacent opposite sides of said disc of electrons, each of said control electrode structures including a plurality of elements mounted in space phase relationship with respect to all of the remaining control elements of its own and the opposite control electrode structure, the space phase relationship being such that said control elements are effective upon application of multiphase operating potentials thereto to produce regularly recurrent disc electron deflection with continuously advancing phase around said cathode, said deflection being in a direction normal to said disc and occurring in the region under'the influence of each of said control elements, and a magnetic flux carrying member having a flux emitting end positioned adjacent the space between said cathode and said anode, said member being oriented to direct flux through said space substantially in the direction of said electron deflection and substantially at right angles to the paths of individual electrons from said cathode to said anode.

11. An electron discharge device including a cathode having an electron emissive area, a segmented anode mounted in coaxial relationship to said cathode, focusing electrodes mounted in coaxial relation to said cathode adjacent opposite extremities of the emissive area thereof to concentrate the electrons emitted from said area into a disc of electrons upon application of operating potentials to said electrodes, a pair of control electrode structures mounted coaxially with respect to said cathode adjacent opposite sides of said disc of electrons, each of said control electrode structures including a plurality of control elements mounted in space phase relationship with respect to all of the remaining control elements of its own and of the opposite control electrode structure, the space phase relationship of said control elements being such that upon application of multiphase operating potentials thereto there is produced regularly recurrent disc electron deflection with continuously advancing phase around said cathode, said electron deflection being in a direction normal to said disc and occurring in the region under the influence of each of said control elements, the number of the segments of said segmented anode bearing an integral relationship to the number of the control elements of each of said control electrode structures, and a magnetic flux carrying member having a flux emitting end positioned adjacent the space between said cathode and said anode, said member being oriented to direct flux through said space substantially in the direction of said electron deflection and substantially at right angles to the paths of individual electrons from said cathode to said anode.

12. An electron discharge device including an envelope, a cathode, focusing means for forming electrons emitted from said cathode into a sheetlike beam, beam deflecting means disposed adjacent opposite outer faces of said beam, said beam deflecting means including at least three mutually insulated conductive portions, each of said portions including a plurality of electron controlling areas, and an anode having a plurality of segments disposed in the plane of said beam, said electron controlling areas being effective upon application. of multiphase potentials thereto to cause an electron density wave to progress at uniform velocity continuously and recurrently along the path of said anode segments.

13. An electron discharge device including an envelope, a cathode, focusing means for forming electrons emitted from said cathode into a sheetlike beam, beam deflecting means disposed adjacent opposite outer faces of said beam, said beam deflecting means including at least three mutually insulated conductive portions, each of said portions including a plurality of electron controlling areas, a first anode having a plurality of segments disposed in the plane of said beam, said electron controlling areas being effective upon application of multiphase potentials thereto to cause an electron density wave to progress at uniform velocity continuously and recurrently along the path of said anode segments, and a collecting anode for collecting electrons passing between said segments.

14. An electron discharge device including an envelope, a cathode, focusing means for forming electrons emitted from said cathode into a sheetlike beam, beam deflecting means disposed adjacent opposite outer faces of said beam, said beam deflecting means including at least three mutually insulated conductive portions, each of said portions including a plurality of electron controlling areas, an anode having a plurality of segments disposed in the plane of said beam, said electron controlling areas being effective upon application of multiphase potentials thereto to cause an electron density wave to progress at uniform velocity continuously and recurrently along the path of said anode segments, and magnetic means for altering the instantaneous velocity of said wave in response to an input signal.

15. An electron discharge device including an envelope, a cathode, focusing means for forming electrons emitted from said cathode into a sheetlike beam, beam deflecting means disposed adjacent opposite outer faces of said beam, said beam deflecting means including at least three mutually insulated conductive portions, each of said portions including a plurality of electron controlling areas, an i anode having a plurality oiv segments disposed in the plane of said beam, said electron controlling areas being effective upon application of multiphase potentials thereto to cause an electron density wave to progress at I uniform' velocity continuously and reeurrently I plurality of spaced conducting areas, each of said control electrodescomprising a plurality of elecalong the path of'said anode segments, anda magnetic flux carrying member having a flux emitting end positioned adjacent the space between said cathode and said anode, said member tron controlling areas regularly spaced from each other, and efiective upon application of multiphase potentials thereto to cause an electron density wave to progress at uniform velocity recurrently andv continuously over said conducting areas.

being oriented to direct flux through said space substantially at right angles to the motion of said wave andsubstantially at'right angles to the paths of individual electrons flowing from 1 said cathode to said anode.

' l6. An electron discharge device: including a 18. An electron discharge device having an'envelope, a cathode, a first anode having a plurality of spaced electron receiving areas, a collecting anode adjacent said first anode for collecting,

electrons passing said receiving areas, and at least 7 three control electrodes, each of said control eleccathode having an electron emissive area, a seg Y merited anode coaxial with said cathode, focusing electrodes mounted in coaxial relation to said cathode adjacent opposite extremities of the emissive area thereof for concentrating the electrons emitted from said area into a disc of electrons upon application of suitable operating potentials to said focusing electrodes, at least one control electrode structure mounted coaxially with respect to said cathode adjacent said'disc ofv electrons, said structure including a plurality of control elements eachmounted in spacephase relationship with respect to' each'of the other control elements of said structure, said space phase relationship being such that said control elements are effective upon applicationvof multiphase potentials thereto to produce regularly recurrent disc electron deflection with continuously advancing phase around'said cathode, said vdeflection being in a direction normal to said disc and occurring in'the region under the influence of each of said control elements, and a magnetic flux directing member oriented to direct magnetic ilux through'the space between said cathode and trodes having a plurality of electron controlling, areas regularly spaced from each other and ef fective upon application of vmultiphase potentials thereto to cause an electron density wave to'progress at uniform velocity recurrently and continuously across said receiving areas.

19. An electron discharge device including an envelope, a cathode, a first anode having a plurality of spaced electron receiving areas, a collecting anode adjacent said first anode vforv collecting electrons passing said receiving areas, at least three control electrodes, each of said control electrodes comprising a plurality of electron I controlling areas regularly spaced from each other and efi'ective upon application of multiphase potentials thereto to'cause anelectron density wave to progress at uniform velocity recur- 'rently' and continuously over said conducting areas, and magnetic means for altering the instantaneous velocity of said wave in response to an input signal.

ROBERT ADLERV I REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,164,922 Hollmann July 4, 1939 2,201,323 Shelby May 21, 1940 2,293,368 Stuart, Jr. Aug. 18, 1942 2,300,436 Skellett Nov. 3, 1942 Certificate of Correction Patent No. 2,460,966. February 8, 1949. ROBERT ADLER It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction as follows:

Column 5, line 53, for the Word sufficiency read sufiiciently; column 6, line 20, for Wtih read with; column 12, line 24, for anode 17 read anode '71; column 13, line 55, for whih read which; column 18, line 74, after wave strike out so;

and that the said Letters Patent should be read With these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 21st day of June, A. D. 1949.

THOMAS F. MURPHY,

Assistant C'ommz'ssz'oner of Patents. 

